This invention relates generally to a self sealing valve which provides and maintains a seal when an instrument or device is inserted through, or withdrawn from, the valve. More specifically, it relates to a flexible, elastomeric self sealing valve especially well suited for use with surgical instruments, such as trocar assemblies necessary for numerous laparoscopic surgical procedures.
Sealing devices for trocar assemblies are an important aspect of the design of instruments used in laparoscopic surgical procedures. A laparoscopic surgical procedure utilizes several small puncture openings, mainly in the abdominal wall, to allow insertion of specialized surgical instruments instead of one large incision in a traditional open surgical procedure. The laparoscopic procedure is becoming widely accepted because of its many advantages such as: less trauma to the patient, shorter recovery time, reduced adhesions, and post operative pain. The laparoscopic surgical technique requires inflation of the abdominal cavity to lift the abdominal wall from the internal organs to create working space for the surgeon and to introduce light generating and optical viewing instruments.
During the laparoscopic surgical procedure, the internal gas pressure must be maintained in order to successfully complete the procedure. In order to maintain the internal gas pressure while instruments are passed into and out of the openings in the abdominal cavity, sealing devices are required for both the instruments and for the trocar assemblies used to make and maintain the small openings. It is desirable for such sealing devices to seal any opening within the trocar assembly when the obturator, which is the puncturing component of the trocar assembly, is withdrawn after puncturing the abdominal wall. It is also desirable to seal when other surgical instruments are inserted through the trocar cannula, which is the hollow tube of the trocar assembly remaining in the puncture opening throughout the remainder of the surgical procedure. Additionally, it is desirable that the seal device produce a small amount of resistance to the insertion force of surgical instruments passing through the trocar cannula. Furthermore, it is desirable that the sealing device maintain gas pressure in the abdominal cavity, despite numerous insertions and withdrawals of surgical instruments through the trocar cannula.
Current sealing devices for laparoscopic instruments are typified by particular valve designs such as that described in U.S. Pat. No. 5,224,952. This design includes a spring loaded valve in combination with a sealing gasket to conform to the cross section of the surgical instrument inserted through the trocar. This two part valve assembly performs adequately as a seal but may be more complex than truly desired. U.S. Pat. No. 5,141,498 shows at least three flexible leaflets, and U.S. Pat. No. 4,424,833 shows a sponge type valve with three connecting slits. Multiple leaflet and multiple slit valves may seal well when a surgical instrument is not inserted through them but will tend to create gaps around inserted instruments having circular cross sections and will also tend to cause eversion of their sealing surfaces when the instruments are withdrawn. Eversion of the sealing surfaces is likely to cause gaps between the sealing surfaces resulting in gas leakage through the seal. U.S. Pat. No. 5,242,412 shows a duck bill valve design applied to a trocar device. This design provides a straight single slit to seal against a surgical instrument. U.S. Pat. Nos. 4,475,548; 4,809,679; and 4,143,853 show single slit designs also. A single slit valve is also subject to a lack of conforming to circular shapes and to eversion upon withdrawal of surgical instruments.
Variations of the single slit design are shown in U.S. Pat. Nos. 4,798,594; 4,177,814; and 4,673,393. The variations shown in these patents encompass three slits radiating from the seal center and possess similar characteristics as the single slit regarding sealing around circular instruments and eversion. Other surgical valves include specialized designs typified by heart valves shown in U.S. Pat. Nos. 4,364,127; 3,861,416; and 4,222,126. These valves are designed to allow one direction flow of heavy liquids and include at least three flaps. Such valves are not intended to seal around surgical instruments against loss of gas pressure.
A study of these references indicates a need for a simpler one piece sealing valve assembly for use in trocars to seal against gas pressure during a laparoscopic surgical procedure. In addition, it is desirable to have a one piece assembly with a simple design which would not require an excessive force to insert an instrument through it and would resist eversion of the sealing edges once the surgical instrument is withdrawn.